A hard disk drive (HDD) is a non-volatile storage device that is housed in a protective enclosure and stores digitally encoded data on one or more circular disks having magnetic surfaces. When an HDD is in operation, each magnetic-recording disk is rapidly rotated by a spindle system. Data is read from and written to a magnetic-recording disk using a read-write head that is positioned over a specific location of a disk by an actuator. A read-write head makes use of magnetic fields to write data to and read data from the surface of a magnetic-recording disk. A write head works by using the current flowing through its coil to produce a magnetic field. Electrical pulses are sent to the write head, with different patterns of positive and negative currents. The current in the coil of the write head produces a localized magnetic field across the gap between the head and the magnetic disk, which in turn magnetizes a small area on the recording medium.
HDDs are being manufactured which are hermetically sealed with helium inside. Further, other gases that are lighter than air have been contemplated for use as a replacement for air in sealed HDDs. There are various benefits to sealing and operating an HDD in helium ambient, for example, because the density of helium is one-seventh that of air. Hence, operating an HDD in helium reduces the drag force acting on the spinning disk stack, and the mechanical power used by the disk spindle motor is substantially reduced. Further, operating in helium reduces the flutter of the disks and the suspension, allowing for disks to be placed closer together and increasing the areal density (a measure of the quantity of information bits that can be stored on a given area of disk surface) by enabling a smaller, narrower data track pitch. The lower shear forces and more efficient thermal conduction of helium also mean the HDD will run cooler and will emit less acoustic noise. The reliability of the HDD is also increased due to low humidity, less sensitivity to altitude and external pressure variations, and the absence of corrosive gases or contaminants.
Electronic systems that require a hermetically sealed internal volume (e.g., a lighter-than-air gas filled, sealed HDD or system of HDDs) need a way of preventing the occurrence of leakage through the interface between a container cover and a corresponding container base to which the cover is coupled. One approach may be to adhesively bond the cover to the base by applying a pressure-sensitive adhesive (PSA) around the component interface, which functions as a barrier to gas leakage and moisture passage. A PSA-based seal offers more reworkability of the seal, as compared to an epoxy seal. Furthermore, a tape seal is a reasonable approach to the use of a PSA seal because a very thin PSA sheet (in the range of 20-100 μm) can be utilized, which can achieve a small diffusion area that aids in minimizing the leak rate. In all cases, the critical diffusion length is the smallest distance through or around the PSA sheet (or simply “PSA”) that the enclosed lighter-than-air gas would need to travel to leak out of the container. In the context of a PSA without a metal layer, this diffusion length would typically equate to the thickness of the PSA sheet, as the gas can diffuse through the PSA. In the context of a PSA having a metal layer to prevent diffusion of the lighter-than-air gas through the PSA, this diffusion length would typically equate to shortest path around, i.e., along the length of, the PSA.
Any approaches described in this section are approaches that could be pursued, but not necessarily approaches that have been previously conceived or pursued. Therefore, unless otherwise indicated, it should not be assumed that any of the approaches described in this section qualify as prior art merely by virtue of their inclusion in this section.